1. Field of the Invention
The present invention relates to a power reserve display mechanism for displaying a remaining amount of a mainspring in a mechanical timepiece constituting a power source thereof by the mainspring.
2. Description of the Prior Art
In a background art, a planetary mechanism (planetary gear mechanism) is normally used for a power reserve display mechanism, with regard to constituent parts such as a sun wheel and a planetary wheel, an input side thereof is directly or indirectly coupled to a barrel complete and a ratchet wheel or a barrel stem, and an output side thereof is directly or indirectly coupled to a display wheel supporting a display hand pivoted in a face in parallel with an extended face of a dial (for example, Japanese Patent Publication No.2757147 and Japanese Patent Publication No.3054943).
However, the planetary mechanism is necessarily accompanied by a number of train wheels and integrated as one set and therefore, a comparatively large region is occupied thereby and also a structure thereof is liable to be complicated.
On the other hand, it is proposed to use a screw mechanism for a power reserve display mechanism in place of the planetary mechanism (JP-A-2003-227883). According to the proposal of JP-A-2003-227883, a male screw wheel and a female screw wheel respectively having gear portions are brought in mesh with gear portions of a ratchet wheel and a barrel wheel, the female screw wheel is provided with a conical portion and the conical portion is engaged with an arm integrated with an indicator, and the arm is pivoted in accordance with movement of the female screw wheel in an axial direction.
According to the power reserve display mechanism disclosed in JP-A-2003-227883, in order to pivot the arm in a face in parallel with an extended face of a dial, the male screw wheel and the female screw wheel are rotated around a rotational axis line orthogonal to the dial and moved relative to each other in a thickness direction of a timepiece.
Therefore, a size in the thickness direction is liable to be enlarged.
Further, in any of the power reserve display mechanisms of the background arts, the indicator is pivoted in the face in parallel with the display face of the dial.
The invention has been carried out in view of the above-described point and it is an object thereof to provide a power reserve display mechanism having a mainspring remaining display showing a novel behavior and a mechanical timepiece having the same.